Creeping traction tread and cooperating tumbler



Feb. 23 1926.

S. R. W. M. BAGER Er AL CREEPING TRACTION TREAD AND COOPERATING TUMBLER Original Filed Feb. '7, 1921 III/IA 7,2,7

:R m? N H H85 mm WR M NE WW 5 A TTORNEY.

40 tures of the present invention.

' Patented Feb. 23, 1926.

UNITED STATES PATENT OFFICE.

SVAN TE R. W. MuIBAGzER AND WERNER LEHMAN, OF SOUTH MILWAUKEE, WISCONSIN,

ASSIGNORS TO BUCYRUS COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF "WISCONSIN.

CREEPING TRACTION TBEAD AND COOPERATING TUMBLER.

Original application filed February 7, 1921, Serial No..443,164. Divided and this application filed October 10, 1921, Serial No. 506,630. Renewed October 31, 1925.

To all whom it may concern: I

Be it known that we, SVANTE R. W. M. BAGER and WERNER LEHMAN, citizens of the United States, residing at South Milwaukee, in -the county of Milwaukee and State of Wisconsin, have invented a certain new and useful Improvement in Creeping Traction Treads and Cooperating Tumblers, of which the following is a full, clear, concise,

and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This invention relates to creeping traction mechanisms and, more particularly, to the endless tread belts and driving tumblers for use therewith.

' One object of the present invention is the provision of an endless tread belt of very sturdy construction, having a relatively broad tread surface and otherwise well adapted for use as a traction unit and support for power excavators and other heavy portable machinery.

Another. object is the provision in an endless tread belt of novel and improved means for effecting a positive drive connection between the belt and the cooperating driving tumbler.

Another object is the provision of a sim- 0 ply constructed driving tumbler of a new and improved design.

Other objects and appear.

One embodiment of this invention is advantages will later 5 illustrated in the accompanying drawings,

in which:

Figure 1 is a side elevation of an excavator supporting frame equipped with a traction mechanism embodying the novel fea- Figure 2 is a vertical'sectional view of a tread belt taken through the axis of a driving tumbler. 1

Figure 3 is a fragmentary side elevation of the parts shown in Figure-'2. v

Figure 4 is a plan view of a pair of conneoted tread belt links.

Figure 5 is a sectional view of one of the tread belt links taken substantially on the line 5-5 of Figure 4.

Figure 6 is a fragmentary edge view of one of the tumblers.

The excavator supporting frame shown in Figure l is substantially identical with the frame described in the copending application of S. R. W. M. Bager, Serial No. 443,- 106, filed February 7, 1921, and in our copending application, Serial No. 433,164,

filed February 7, 1921, of which this application is a division. It will suffice here to 00 say that this frame is substantially rectangular in form and includes a pair of longitudinal side sills 10 in the form of heavy I-beams and a plurality of transversesills 11, connected together and braced by an annular rack and track member 12 constituting a turn-table support for the heavy excavating machinery (not shown) ordinarily revolubly mounted thereon.

The traction mechanism herein shown is also substantially identical with that disclosed in our copending application last above identified. This mechanism includes a pair of endless tread belts 13 mounted on either side ofthe frame and passing around the front and rear wheels 14 and 15 thereof. Additional frame supporting wheels 16 are provided on each side of the frame intermediate the front and rear wheels. Each of these intermediate wheels 16 bears upon the lower run of the belt and serves to sustain the upper run thereof against excessive sagging.

The several wheels 14, 15 and 16' are mounted upon shafts 17 separately connected with the frame. Each wheel comprises a relatively wide hub 18, and a relatively narrow rim 19 integrally connected by a web 20, reinforced by radial stiffening ribs 21. These wheels, though of comparatively light construction, are well able to sustain the heavy loads and transverse stresses imposed thereon during continued use. The rear wheels 15 constitute the drivingtumblers, and for this reason each is provided along the rim thereof with a series of projections 22 constituting driving lugs which cooperate with the tread belt in a manner to be later described to establish a positive drive connection therewith. These lugs 22 are preferably arrangedat the junctures of the ribs 21 with the rim.19.

Each tread belt is made up of a series of hingedly connected links 23 which together 3 constitute a substantially continuous relatively broad tread surface for engagement with the ground. Each link comprises a casting, preferably hollow for purposes of lightness, having an outer wall 24: constitut- 1e ing the tread portion thereof. stiffening ribs 245' project inwardly from the wall 2 and merge into the skeleton inner wall 25, which carries a pair of centrally disposed parallel flanges 26 spaced apart a distance corresponding to the width of the rims 19 of the several wheels 14, 15 and 16. The flanges 26 of the several links extend longitudinally of the belt and together define a centrally disposed wheel receiving guideway 20 or channel along the inner face of the belt. Each link 23 extends somewhat beyond the ends of the channels 26 so as to provide a space between the ends of the channels of adjacent links for receiving the lugs 22 of the driving tumblers 15. A positive drive connection isthus established between the driving tumblers and the tread belts.

The several wheels 14, 15 and 16, embraced within each tread belt, engage within and 30 travel along the guideway defined by the flanges 26, that portion of the inner wall 25 ofeach link, constituting the base of the i guideway, being'substantially flat so as to provide a substantially smooth track for the intermediate wheels 16. The peripheries of the wheels 14, 15 and 16 are circular, except for the flattened portions 30 formed upon the periphery of each of the driving tumblers 15 intermediate successive lugs 22.

4 These flattened portions are-sufficiently extended to afford ample bearing contact between the driving tumblers and their cooperating links 23, to sustain the pressures and to insure proper engagement of the lugs 22 between the ends of adjacent flanges 26. At

the same time the flattened portions are not so extended or pronounced as to cause a bumping action ofv the tumblers as they engage and roll along the lower run of the belt. In the mechanism shown (Fig. 3),

each flattened portion 30 occupies substantially the middle one third portion of a sector comprised between adjacent lugs 22.

It has been found that the driving faces of the lugs 22 and ends 31 ofthe flanges 26 1 should be curved in order to obtainmaximum driving surfaces, and yet insure ample clearance of the lugs 22 during engaging and disengaging. Practical experimentation has demonstrated that the best results are attained when'each end 31 of the flanges is ofconcave form presenting a curved face whose center of curvature is disposed in line with or above the upper or free edge of the flange, and when the driving faces of the and held in place by' small retaining pins lugs 22 are of convex form of similar curvature. In the mechanism shown, particularly in Figure 3, the center of curvature of each concave end surface 31 of a flange 26 is located in line with the free longitudinal edge of the flange and in position where it substantially coincides with the center of curvature of the abutting face of a cooperating lug 22 when the end of the flange is in driving relation therewith. The radius of curvature of the driving faces of the lugs is preferably a trifle less than that of the driving surfaces of the flanges. The upper portions of the driving surfaces 31 are preferably reversely curved or otherwise slightly modified to insure ample engaging and disengaging clearance between the lugs and flanges.

The links are hingedly connected, referably at points adjacent the outer e ges of the belt, so as to/ provide an exceedingly sturdy construction. For this purpose, each link is provided at one edge thereof with a pair of pivot ears 27 spaced a substantial distance beyond the flanges 26, the intermediate portion of the edge remaining substantially straight for purposes of strength and rigidity and to permit a close fit with the adjacent edge of the adjoining link. The other edge is substantially straight except for appropriate recesses formed therein to snugly receive the pivot ears of the next adjacent link. Pivot pins 28 are passed through the interengaging parts thus formed 29, which extend through the ends of the pivot pins and are engaged in adjacent corners of the corresponding links.

It will be noted that each belt is engaged only in the central portion thereof by tl1e, several wheels 14, 15 and 16.- Furthermore, the wheel rims and consequentlythe wheel receiving channels are very narrow relative to the width of the belt. The flanges 26 are thus disposed well within the outer edges of the belt where they and the channel de fined thereby remain comparatively free and clear from foreign matter that might climb over the edges of the belt.

. Various changes may be made in the embodiment of the invention hereinabove described, without departing from or sacrificing any of the, advantages of the invention I as defined in the appended claims. 1

We claim:

1. An endless tread belt for creeping traction mechanisms comprising a series of tread belt links, each having a broad ground engaging surface on one side thereof, a single centrally disposedwheel engaging surface on the other side thereof for receiving the load, wheel guiding means associated with said wheel engagingsurface, laterally spaced means at one edge of each link in the plane thereof for connection with the next I adjacent link, said means being disposed at to prevent the passage of foreign matter therebetween.

2; A'tread belt link for creeping traction mechanisms having a broad ground engaging surface on one side thereo posed on the other-side thereof, the base of said channel being substantially flat to form .a' smooth runway for the Wheels, 9. pair of pivot ears'on one edge of said link arranged "at opposite sides of said channel, and a pair of recesses in the opposite edgerof said link for receiving the pivot ears of an adjacentlink, the edge portions of said link intermediatesaid ears, and said recesses being substantially straight for purposes of rigidity and to permit a close fit with adjacent links. r

3, A tread belt for creeping traction mechanisms comprising a series; of connected links, 'each' link having a relatively broad tread surface, a flat, relatively narrow, centrally disposed wheel engaging surface, wheel guiding means associated with said last named surface, a pair of ears integrally formed on one edge of each link, in the" plane thereof, said ears being disposed at opposite sides of said last named surface,

recesses formed in the opposite edge of each link for receiving the ears of an adjacent link, and a separate pivot pin associated with each ear.

4. In-a creeping traction unit, the combination of a series ofwheels including a driving tumbler and an endless tread. belt trained about said series of wheels, said belt comprising a series ofclosely associated links forming a substantially unbroken tread surface on' one side and a narrow centrally disposed surface on the other side on which all of said wheels enga e, and laterally spaced hinge connections etwcen I a single nar-. ,row wheel receiving channel centrally discombination of anendless tread belt comprising a series of connected links, each link having a relatively broad tread surface, upstanding flanges, and a flat surface between said flanges forming a substantially continuous roller path, a tumbler disposed to travel along said path, and lateral lugs on said tumbler for driving engagement between the flanges of successive links, the periphery of said tumbler being flattened between successive lugs permitting deep engagement of said lugs between said flanges.

7 In a creeping traction mechanism the combination of a tread-belt comprising a series of connected links, each comprising an integral casting having a relatively broad tread surface, upstanding wheel-guiding flanges and a single centrally-disposed wheel-engaging surface of such narrowness as to render the tread-belt laterally flexible so that it will accommodate itself to lateral irregularities in the ground surface, a driving-tumbler disposed between said flanges, and lateral lugs on said tumbler disposed for driving enga ement between the flanges of successive li s. 1

In witness whereof, we hereunto subscribe our names this 4th day of October, 1921.

SVANTE R. w. M. BAGER. WERNER LEHMAN. 

